Hi, and welcome to the RSM250 world! I have been running an RSM250 for a year and a half now, and it's a great setup. The only thing that I quickly had to invest in was a chiller, and a bigger pump to drive the chiller and circulation nozzle on the right. The RSM250 manual says that you can add another pump to the right hand chamber to drive the chiller, utilising the above mentioned accessories panel in the back, with the return from the chiller back into the same chamber.
I found that setup a bit strange, since it means that you return the chilled water back to the same chamber from where you pump the water into the chiller. Didn't work great IMO, even though some of the chilled water is being pumped into the tank with the original circulation pump. I got the advice in here, which I followed, to replace the original pump with a larger one, take the output from the pump via the accessory panel to the chiller. The return from the chiller goes back through the accessory panel directly to the return nozzle into the tank. This works very well.
I hope you could understand what I meant, and I would have posted some photos if I knew how to add pics to threads (have failed miserable so far in my own new RSM500 thread, with nobody answering my cries for help so far).
Best of luck with your tank, I'll be happy to share any other knowledge I have picked up along the way by making mistakes, just let me know.